1. Field of the Invention
The present invention relates to a barrier apparatus for opening/closing an opening portion provided in a front surface of a photographing optical system, and an image pickup apparatus including the barrier apparatus.
2. Description of the Related Art
To protect a front surface of a photographing optical system such as a lens barrel of an image pickup apparatus from damage or dirt, a barrier apparatus for opening/closing an opening portion provided in the front surface of the photographing optical system has been known. For example, as disclosed in Japanese Patent Application Laid-Open Publication No. 8-220595, a barrier apparatus has a function of opening/closing an opening portion provided in a front surface of a photographing optical system with a plurality of blade-shaped shielding members movable into and out of the opening portion.
As a barrier apparatus for opening/closing an opening portion with a blade-shaped shielding member, a configuration is known in which a shielding member is rotated around a support shaft provided around an opening portion and thus moved into and out of the opening portion. In the barrier apparatus having such a configuration, a power point for inputting a driving force is provided at a position radially apart from the support shaft in the shielding member to apply moment around the support shaft to the shielding member. For example, a configuration is perceived in which a power point for inputting a driving force to a shielding member is provided on a side closer to a center of the opening portion than the support shaft.
Also, the barrier apparatus is desired to be reduced in diameter for reducing a diameter of a lens barrel. Thus, as disclosed in Japanese Patent Application Laid-Open Publication No. 8-220595, the barrier apparatus has a configuration in which a plurality of shielding members open/close the opening portion to reduce a width of the shielding member so that an inner diameter of the opening portion is larger than an outer diameter of the apparatus.